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Chapter 5, FRONT PANEL OPERATION
5.4.02 Virtual Reference Main Display
5-60
Figure 5-46, Main Display - Virtual Reference Mode
In virtual reference mode, the instrument operates exactly as in single reference
mode, with the following exceptions:-
The Main Display always shows the annotation "Virtual Reference Mode" in the
bottom right-hand section of the display as a warning to the user that this mode is
being used.
Although the upper three display positions can be reconfigured to display magnitude
and/or phase information, neither of these is relevant since there is no reference
signal to which the phase can be related, and the magnitude equals the X channel
output. Similarly, controls affecting the instrument's reference phase, such as Ref
Phase and Ref Phase ±90°, have no effect and are grayed out.
Harmonics greater than unity should not be used in virtual reference mode since the
harmonic number relates to the reference frequency. Nevertheless, detection at
harmonics of the signal frequency is possible by searching for the required harmonic
frequency. For example, if the signal frequency is 1 kHz and a measurement at the
second harmonic is required, set the harmonic to 1st and search for a signal at 2 kHz.
The signals at the OSC OUT connector on the front panel of the main console or at
the 7124 RCU (depending on which output is activated) and the REF MON
connector on the rear panel are at the virtual reference frequency.
Since none of the controls on the Reference menu are relevant, it is not possible to
access it.
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